How high? It is supposed to be high(er). Around 12-1300 would be ideal. You have an air auxilary valve (AAV) next to your WUR that also works on a bimetallic finger with heat and when cold allows extra air thru for the extra fuel your cold WUR lets thru. In theory, they work in tandem and heat up together and close the AAV off as the WUR closes up. Then your idle should drop to around 900 rpm. Often, idle problems are due to a sticky/faulty AAV. (easy to check and fix).
Alan